The take-away message is that behavior change is complex and that knowledge is a necessary but insufficient agent for change. Following the tenets of Social Cognitive Theory,20 physicians might also need to address patient motivation, confidence, outcome expectations, and skills to help promote behavior change.
Strengths and limitations of this study
We recorded conversations rather than relying on physician or patient recall. Additionally, these primary care patients were not enrolled in a weight-loss trial and, therefore, were not self-selected to be highly motivated to lose weight. Because of this, and the large and ethnically diverse sample, our results should be generalizable to many clinical settings.
One limitation is that few younger, lower-income patients were included in the sample, which limits generalizability to those populations. Also, the study was observational. Although we adjusted for a broad set of patient, physician, and visit covariates, unmeasured confounding variables may still account for at least part of the observed associations. The analysis is limited by the use of self-reported dietary fat intake and physical activity measures. A food diary and accelerometer would have been more accurate; however, such involved measures could invoke changes in behavior, which would have confounded our ability to assess the effect of physician advice on weight loss.
Acknowledgements
The authors thank all of the physicians and patients who participated in this study, the study project managers Gretchen Yonish and Iguehi Esoimeme, and research assistant Justin Manusov.
CORRESPONDENCE
Stewart C. Alexander, PhD, Department of Medicine, Duke University School of Medicine, P.O. Box 3140 Medical Center, Durham, NC 27710; alexa045@mc.duke.edu